So bust is my memory now, that often when I meet people I've known for years, I have to mentally work through a list of first names before I can do that American thing of mentioning theirs, as in "You're quite right, Mary." My husband's memory is so pristine for people he once knew (and for their best cricket scores) that when the invitation to a school reunion arrived, he was able instantly to recite the school register of five decades ago. Surnames, naturally, for, as he once wrote in a essay called Mummy, Matron and the Maids, all that was personal, vulnerable, and contaminated by home was locked away in the boys' unused first names.

We hesitated over whether to go to the thrash at what he insists on calling his "minor public school" (I've yet to meet anyone who admits that theirs was major.) The people he'd find most intriguing to meet, he thought, might be the ones who wouldn't want to return. And on the subject of public schools, I'm pretty much sealed in prejudice: they're iniquitous places that prepare their charges for empire and elite, tearing young children from the bosom of their families at an unbearably tender age so that they carry around for life the scars of premature separation, etc etc. I knew I was going to meet lots of people of the "it never did me any harm" school.

In the end we decided to go. My chosen identity for the occasion was that of anthropologist: I was going on a field trip (to another planet?) Driving through the English countryside at its most verdant and lush, my husband recalled making up a cruel rhyme about a prefect that caught on among his classmates, and wondered if it would be remembered.

We reached the marquee, sheltering more blazers than I've seen in a lifetime. I was too young to be taken for a wife but too old to be a daughter. My husband and his peers wandered about, scanning each others' faces, looking for the boy in the man, and trying to see what time had done.

A lot. The scattiest young thing had worked for MI6, and was now an urbane, charming City chap, with elegant wife and grandchildren. There were high commissioners and accountants and doctors, but few others, I guess, with children still in primary school.

In the end that thing happened. I got chatting to a Lady, and she became just a lady, another person proud of her grandchildren and wondering how best to help a sick daughter. The men - the establishment enemy! - started to seem touching in their continuing zest and ability to connect with their younger selves, even if these were mostly located on the cricket or rugby pitch. (The former prefect had no recollection of my husband's rhyme.) Interesting how people like me, who wouldn't think of treating asylum seekers as anything other than people deserving of respect, have no compunction in dehumanising the powerful or once powerful.

I've been to a number of reunions of my own. At the first, just after I'd had a baby, it was those frumpy girls I'd looked down on at school who provided me with most comfort and reassurance of life after babies. It's hard to put on airs with people who knew you in a gym slip, before you've affixed your adult persona, although the re-encounter with one's younger self isn't always enthralling. At a workplace reunion last November, I met up with people who knew me in my first job, when apparently I was permanently cheerful.

There's always some element of competitiveness in reunions, especially among women: who has the most kids, the least number of marriages, the swishest job? After a few decades you get to see the lie of the land - how life has treated you - and compare. There's a person who's had to deal with a child with disabilities, another with a dying husband. There's the rebel who was perpetually doped and is now altogether matronly. You also see the narrative that people construct about their lives, which may be quite different from the reality they've faced - the woman who feels cheated, besides one who "can't complain" although she should. And, sometimes, well before you're ready to confront the fact yourself, you note the names of those who've died.

What reunions at their best do is inspire respect - for people's capacity to cope with what life throws at them, and for the inexorability of the life-cycle.